Catharine "Cat" Carnahan grew up on the Erie Canal, working side by side with her father on their boat, towing freight from Albany to Buffalo. Gutsy and independent, she holds her own with the roughnecks who work the canal, including the brutal, lascivious Simon Maphis. She has yet to discover her own passionate nature --- until she and her father rescue a mysterious stranger who has been beaten by thugs. His head woulds have left him with no memory of his past, but his gold pocket watch identifies him as Morgan Kane. Obviously a gentleman, he gratefully accepts Cat's offer to recuperate aboard the boat, doing odd jobs for his keep. It is Morgan's presence that finally awakens Cat to her own womanhood. And it is Morgan who fulfills her passion one languid evening on the canal.

But Cat's new-found love turns to revulsion when Morgan becomes involved with the lottery company that has ruined the lives of so many canal men, taking their hard-earned cash in exchange for false promises of instant wealth. What she does not know is that Morgan's memory has returned --- and that he is on a dangerous mission to expose the corruption of the lottery by working from the inside.

Rejecting Morgan, Cat tries to forget him in the arms of an idealistic young doctor who serves the canal families. But when Simon Maphis, infuriated by Cat's many rejections, tries to kill her and her father --- and succeeds in destroying their boat --- Morgan returns, determined to claim her, tame her and marry her. Investing in a new boat, he persuades Cat to try for the most coveted cargo on the canal --- the U.S. Mail. But Simon Maphis has not yet finished with his evil schemes.